Eastern and Western way
There is "Eastern" spirituality with Zen, meditation and Yoga in many shapes and flavors. There is Christian spirituality. There are New Age - like spiritual schools with "astral projections" and extraterrestrials.
Is there anything more suitable for Western people? Something, that does not require sitting in a weird position, denying scientific facts, believing in odd things, memorizing and repeating weird words, yet boosting spiritual power? Is there something built around logical reasoning and common sense?
Steve Pavlina tried to describe what Western spirituality is , and F. Vaughan did a very good job too , but it is still quite incomplete. Ann-Kristin Peterson and Jurg Rohrer  did very good attempt too, but they still rely on "angels and other spiritual beings". In this article I try hard to show you the whole picture of true Western way of building up Spiritual Power.
By the way, Western way does not automatically ban Eastern techniques. In fact, many clearly Western schools, like gestalt therapy , or meme guy Richard Brodie in his "Virus of the mind"  encourage using meditation. That's ok as long as it does not block logical reasoning and common sense.
What is "Spirituality"
So what is "Spirituality"? It is mix of five ingredients:
1. Believe in yourself
2. Peace of mind
3. Unconditional love
4. Conscious living
5. Big Life Purpose
What is "Spiritual Power"
Why do I say "Spiritual Power", not "Spiritual Intelligence" like others? What kind of Power I'm talking about?
It is Power to protect yourself and Power to achieve your Big Purpose. It is easy to upset and discourage a person without Spiritual Power, make her feel bad, exhausted, worthless, make her hate others and become unmotivated to do anything. Compare it with spiritually empowered person on a mission to achieve her Big Purpose. You see, this is all about strength and power. If you have the Power, you are free; otherwise every negative or discouraging word you hear enslaves you and holds you like a handcuff.
Many facts can be verified. For example, ice melts into the water. There is no sense to believe or not to believe in facts. There are also purely random processes. They could be accurately described by statistical laws, and "faith" is not applicable to them either.
Faith refers mainly to the non-obvious and non-random events in the future, which people can influence. Faith mobilizes the will, i.e., allows us to take decisions and stick to them, and leads to outcomes that would otherwise be unachievable.
If you believe in victory, your odds to win are much higher. If you believe that you cannot do something, then most likely you will not be able to make it.
Without a strong faith it is impossible to lead people, you can only follow.
Peace of Mind
Peace of mind means lack of anxiety, uneasiness, and panic, regardless of external circumstances. It is calm, confident look into the future.
"Conditional love" is love for something, let's say, for money. I suspect, that it is not love at all. "Unconditional love" means love without conditions, just love. In the other words, not love-because-of, but love-despite-of. In the context of spirituality, "love" is used in boarder sense, including affection, compassion and empathy.
Live consciously means perceive yourself, others and the World, as-is, not the way we would like it is; stop fooling yourself, stop hiding from reality, stop pretending things you do not like do not exist, stop living in imaginary world; admit your desires, your weaknesses, your problems, and your dreams; understand yourself; minimize your cognitive biases ; get out of denial.
Steve Pavlina wrote excellent article on the topic: "The Courage to Live Consciously" .
What is Big Purpose of your Life
"Big Purpose" means solving future problems of mankind that do not have proper solutions yet.
You see - watching sport on TV is not the Big Purpose. No matter what motivational speakers tell you, building wealth is not a spiritual goal, and not the Big Purpose.
Just "doing your work" is not a Big Purpose, even if this work benefits many people.
Let me say it again. It shall be challenging problem with no good known solution, and solving this problem shall help people to live better in the future. You shall devote your life, or at least your spare time, to finding solution and solving it.
Here are few examples: helping kids to grow into happy, healthy and smart adults, caring about future environmental problems, struggling for Peace in the World, doing scientific research in a new field, building up spiritual power of your country and mankind.
You are not likely to be paid for it, and you might not be understood by most of the people. That's Ok. It is just like meditation - people do it for spiritual, not financial or social benefits.
You might get a better idea of Big Purpose relationship to other purposes by looking at purpose map . Big Purpose is highlighted with green there.
Why do you need spiritual power?
Spirituality improves quality of life. Person who loves, do not worry, believe in herself, live consciously, and has a purpose, feels better than a person who hates, worries, waits for failures, hides from reality, wastes her life, yet tries to convince herself it is the best possible option for her.
Spirituality frees up energy that was spent on anxiety, uneasiness, negative emotions, self-deception, and redirect it to constructive purposes.
Spiritual growth boosts physical health. Hiding from reality often hurts eyesight. A lot of health issues are connected to peace of mind. It is hard to stay healthy without help from spiritual side. It is easy to stay healthy if you are spiritually strong. Sorry, but even with all the Spiritual Power, you still need good nutrition and exercises.
Spiritual power comes with purpose of life. It makes life meaningful.
How to build up spiritual power
Let's say, you pull something big, like barbeque machine, through the bushes. Let's say, it got caught on branch. You have two options - pull harder, or try to unhook the branch. For the best results, you can do both. Same thing applies to the spiritual growth. First let's see where we got caught.
What holds you back
People do not believe in themselves, stay anxious and nervous, fence off from people and fight with them, hiding from life - because they are forced to. We all have psychological problems, which largely determine what we think about ourselves and others. These problems get accumulated since the childhood, and prevent us from growing spiritually.
If you parents told you, that you are not able to do things, you are not capable of making the right decisions, only they can, then the growth of your self-confidence is blocked.
If your parents told you, that something bad would happen to you unless you precisely obey all their rules, or if they panicked a lot, then your inner peace is out of reach.
If your parents "loved" you conditionally, or did not let you love them; or if you saw a lot of anger, hatred and revenge around you, it is hard to love unconditionally and accept love from others.
When you want to hide from reality, or suppress your desires or emotions, is just a protective reaction of your mind.
Before pushing mind to the conscious life, it would be nice first to ensure yourself that you do not have to be ashamed of yourself or afraid of being punished.
These problems need to be addressed and treated. They are pretty standard, well studied, and surely treatable by psychotherapy professionals.
How to protect yourself
In a meantime, you can do something for yourself too. First, you need to separate part of you that need help from the part that can provide it. There are multiple models of mind. For our practical purposes, Eric Berne's Parent-Adult-Child model from Transactional Analysis  would work better, than classical Id-Ego-SuperEgo  due to limitations of "Id" concept. Remember, though, that there is no real "Child" inside of you, it is just a convenient name for some phenomena. Please do not expect it to act exactly like a real-life child, or like yourself in a childhood.
As soon as you logically separate your mind into "adult" and "child" parts (and ignore "parent" part for now), you will see, that when YOU get mad, or upset, or offended, it likely your "child" part feels it this way. When somebody tells something not true, but discouraging, you understand, that it is not true, yet become discouraged, it is the adult part that understands that it is not true, yet it is "child" part that gets discouraged. When someone manipulates you, she indeed manipulates your "child" part.
When I first looked at my mind from this prospective, I was really sorry for the helpless and suffering "child" part that is not intelligent enough to separate truth from lie and cannot resist manipulations, and for "adult" part that is intelligent, but does not realize that it can protect the "child" part and how beneficial it will be for the both.
I immediately made a commitment to take care of the "child" part. I promised to guard and protect it, do not let anybody discourage, manipulate or just upset it. I promised to calm, comfort and reassure it every time it is scared or anxious.
Previously, when someone told something bad about me, it went straight to the "child" part and accepted with no questioning, weakening me. Now I first ask: "Is this true"? Usually it is not. If it is still true, "adult" shall deal with it, not the "child". It shall analyze the circumstances and do some corrective actions.
Same thing with attempts to scare me and make me jitter, or make me feel bad about other people, or raze my self-confidence, or make me act out of someone else's assumptions that are clearly not true.
Little by little, I'm building up trust between my "adult" and "child" parts, and feel much stronger.
Eric Berne suggests that we need to make "adult" part more mature. I agree, but I'm also trying to raise and strengthen the "child" part.
What contributes to spiritual growth
Just to get the concept is a big step forward. Making commitment to pursue spiritual growth is the second big step forward.
Spiritual power is not an attribute; it is a skill set you got build up. Even if something very bad happen and shake your peace of mind, love, and faith in yourself, this skill set will help you to stay strong and recover fast.
When you start looking at problems and obstacles as opportunities for building up you spiritual skill set, your spiritual growth will become sustainable and irreversible.
How to build up faith
Steve Pavlina says that some beliefs encourage and energize, while some other ones are discourage and weaken. We must cultivate in ourselves the former ones, and get rid of the latter ones.
Empowering beliefs have nothing to do with fooling yourself. It is quite easy to tell them apart.
For example, convincing yourself that you are the strongest man in the world is likely to be self-deception. Convincing yourself that you can achieve success in what you would like to do is a good empowering belief.
Do not settle for other people's assessment of you. You and only you decide who you are and what you can accomplish.
How to achieve peace of mind
At the first glance, peace of mind is easier to achieve if there is an external force takes care of the future. Followers of many religions put their fate into God's hands, and do not you worry about it, at least in theory. On practice, though, how do you know what God decide to send your way tomorrow? With or without the God, it is not possible gain the full control over your future, or expect only good things.
The only way to achieve true piece of mind is to be ready to accept whatever tomorrow will bring, and do not worry in advance.
How to boost unconditional love
The recipe is simple - just love people and care about them. People commit ugly things to each other and to you, just because they lack spirituality, because they are afraid, nervous, they panic, they do not fully realize what they do, they suffer from their psychological problems, and they often simply see no other choice. Same people could be kind, wise and loving, they just need to grow spiritually.
Help them, but let them do it their own way.
Take a closer look at people; try to understand their problems, their motivation, their emotions. It will help you to feel liking instead of wary.
How to live consciously
Just as carefully as you inspected others, take a look at yourself. What do you really want? What do you disallow yourself to dream of? What are you trying to avoid? What drives you mad? What keeps you awake at night?
As your spiritual power builds up, many of your problems disappear. However, in a meantime you got to deal with all the internal guards of your mind. You know how many fingers you have, what is your height and weight. Structure of your mind is at least as important. Please find courage to learn it even if you do not like some parts of it.
How to find your purpose and what to do with it
When you do job you do not like, and you reach the point where you cannot move forward, you are likely to use it as an excuse and stop.
You are likely to have many huge obstacles on the way to your Big Purpose. It means, that you have to not just like what you are doing - it got to be your passion.
Everyone have a passion, but not everyone let herself to pursue it. You got to do two things - unleash your passion, which will be easy as your spiritual power build up, and to find a way for your passion to serve people.
It is Ok to start with something small, like couching school sport team, as long as you are committed to move on to bigger goals like keeping all the kids in your city off the street.
You are self-sufficient
You no longer have to depend on other people emotionally. Anything other people can give you, you can give yourself. I'm talking about self-confidence, energy, comfort, peace of mind and other good feelings.
Be patient and persistent
Spiritual power is a skill set. Like any other skill set, it takes time to build up. Be patient and persistent.
Groups, Nations and Mankind
Concepts of "Spirituality" and "Spiritual power" are applicable to groups of people too. Some groups grow spiritually, while some others - degrade and eventually disappear. People from those groups are spread and assimilate into some spiritually powerful groups.
Good leader helps his people to grow spiritually. Bad leader teach not to believe in yourself (to convince people that they need him for survival), intimidate, pretends enemies are everywhere, alter what they think about themselves, distort and misinterpret their history. Bad leader imposes bad purpose. Of course, purpose like "make the leader rich" is bad. However, there were guys like Hitler who came up with and imposed their people much nastier purposes.
Bad leader sacrifices spiritual power of her people for sake of power over people.
When I look back, I feel shocked. I'm pretty sure people believe that I was happy and successful man, but my quality of life was really bad. Well, it might be considered way better than average, but then I'm really sorry about the average. It was so painfully hard for me to figure out what the spiritual power is, and how it works. But as soon as I got it, it is so easy to build it up, and immediate benefit is really huge. I no longer have to hide myself behind masks. I no longer feel obligated to pretend to be super-brave and ultra-honest and logical and funny (which often looks silly for other people). It does not mean I no longer smart or brave or honest or silly. It just means I no longer jitter or do stupid things out of silly unconscious preconceptions. I worry at least 10 times less than before, yet I keep track of all risk factors better now. I no loner need somebody to "activate" me, and I no longer have to seek approval from other people. I'm very glad to share all my findings with you and to help you to find the true happiness.
There are many people who can benefit from this knowledge if they would only know about it. Have you seen kids who afraid to try and do not believe in themselves? Have you seen spiritually powerless people who cannot control their own life and make people around them suffer? You can give them something they really need most - information. I will be glad if you send this link to all the people you care about, tweet and blog about it. If somebody does not have a computer, print him or her a copy of this page.
 Steve Pavlina, "Spirituality vs. Intelligence"
. Vaughan, F. "What is Spiritual Intelligence?" Journal of Humanistic
Psychology, Vol 42, No. 2. Spring 2002, 16-33 ? 2003 Sage Publications.
 Ann-Kristin Peterson and Jurg Rohrer, "Spirituality: spiritual growth for a higher consciousness"
 Gestalt therapy
 Richard Brodie, Virus of the Mind
 Cognitive bias
 Steve Pavlina, "The Courage to Live Consciously"
 Purpose Map
 Transactional analysis
 Ego, Superego and Id